There are more studies out there, but here are a couple I know of offhand, showing a 25% to 55% boost.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4945566

https://arxiv.org/abs/2302.06590

The METR study that you're likely talking about had a lot of nuances that don't get talked about, not to mention outright concerns e.g. this one participant revealed he had a pretty damning selection bias:

https://xcancel.com/ruben_bloom/status/1943536052037390531